Signaling system



April 1940. c. .1. FITCH SIGNALINGSYSTEM Original Filed Dec. '7, 1954 mmmw N r R 5 mm L; I

M mn lNV ATTORNEY Patented Apr. 2, 1940 UNITED STATES SIGNALING SYSTEMClyde J. Fitch, Endicott, N. Y., assignor to International BusinessMachines Corporation, New York, N. Y., a corporation of New YorkOriginal application December 7, 1934, Serial No. 756,443, now PatentNo. 2,153,178, dated April 4, 1939. Divided and this applicationDecember 21, 1937, Serial No. 180,968

Claims.

This invention relates broadly to signaling systems and moreparticularly to an electronic impulse generating and selecting system,and is a division of the co-pending application Serial No. 756,443,filed December 7, 1934, now Patent No. 2,153,178, granted April 4, 1939.

An object of the present invention is to provide a signaling systemutilizing timed signals comprising entirely electronic control means andassociated circuits to initiate and receive the control signals.

Another object is to provide a system in which a predetermined number oftimed signals are initiated and a receiver adjusted to be operated onlywhen the said predetermined number of signals are received.

Another object is to provide a synchronously operated system withoututilizing mechanical mechanismsthus providing a system embodying staticelements having less inertia.

Further objects of the instant invention reside in any novel feature ofconstruction or operation or novel combination of parts present in theembodiment of the invention described and shown in the accompanyingdrawing whether within or without the scope of the appended claims andirrespective of other specific statements as to the scope of theinvention contained herein. The present invention is shown and describedin .the said co-pending application in conjunction with a printingtelegraph system; however, it is obvious to those skilled in the artthat this invention is not limited solely to application in suchsystems. For example, the circuit arrangement shown per se in thepresent application may be used to control the operation of any numberof indicating devices utilizing individual control impulses or aseriesof timed control impulses,

In the drawing: i

Fig. '1 shows diagrammatically a preferred arrangement of. theelectronic impulse generating and selecting system.

Figs. 2 to 4 show graphic representations of the different wave formsexisting in different sections of the circuit arrangement.

Referring now to Fig. 1, the signal generator is shownin one form'tocomprise an electric discharge device In comprising the combination of afull'wave rectifier and triode in one envelope andis atype known intheart as a duplex diode triode type. The diode plates II and 12 areondary Winding H of transformer IS. The center tap of the said resistancis connected to the grid element l6 of the tube and is also connected toa second resistance l1 inserted between the said center tap and thecathode element l8. The triode plate I9 is connected to a set of controlelements such as contacts 20 which are included in a circuit comprisingthe primary winding of transformer 2| and battery 22 connected to thesaid cathode element. The secondary winding. of the transformer 2| isassociated with any desirable type of transmitting device known in theart or may be connected directly to the transmission medium whenever itis suitable to do so.

It is evident from the description of the circuit connections just setforth that normally the grid element l6 of the tube is at zero bias, dueto the fact that no current is passing through the resistance l1;therefore, upon closure of the contacts 20 current flow will beestablished in the triode plate circuit as follows: from the positiveterminal of battery 22 through the primary winding of transformer 2|,contacts 20, anode I9 and cathode N3 of the tube to the negativeterminal of the said battery. However, the condition just describedexists in the said circuit for only a comparatively short time, becausethe bias on the grid I6 is not a constant factor but varies in a timedrelationship with the frequency of the A. C. supply source. The saidsupply is impressed uponthe full Wave rectifier and, therefore, therectified voltage impressed on the resistance 11 immediately drives thegrid bias negative wtih respect to the cathode which is of suflicientvalue to prevent further flow of plate current in the triode outputcircuit, but

'as mentioned before the grid bias becomes efiective to reduce the platecurrent to substantially zero value, a pulse is impressed upon theoutput circuit of. the triode in which the transformer of well knowntransmitting means 23 on the transmission'medium. If the contacts 20 aremaintained in an, operated condition for a number 'of complete cycles,of the current supply. source, a controlpulse is initiated automaticallyeach time the current value of the rectified supply passes through zero,thus initiating a series of,

equally spaced and timed: control, impulses. 3y referring tothe graphicrepresentations in Figs. 2

to 4 the voltage coruiitionsv in the' 'various sections of the circuitareshown; .Fig. 2 'showsthe alternating voltage supply. wave} forms,impressed on the diode plates; Fig. 3 shows the rectified voltage waveforms impressed on the resistance l1;

and Fig. 4 shows the series of short equally spaced and accurately timedpulses or control signals impressed on the triode output circuit.

The circuit just described has shown one method of converting a singlephase sinusoidal wave into a series of short impulses havingnonsinusoidal wave forms, all of which are similar, and that in the saidcircuit two impulses are initiated for each complete cycle of thealternating voltage supply.

The signal receiving means comprises in part an electric dischargedevice 24 similar to the device I 0 described hereinabove, and similarassociated control circuits so as to control the operation orconductivity thereof similarly as described in respect with the deviceIll. The diode plates 25 and 26 are connected to the secondary windingof transformer 21 and the shunt connected resistance 28. The primarywinding of the transformer 21 is connected to an A. C. supply sourcewhich is in synchronism with the supply source connected to the primarywinding of transformer I 5. Thus, the said supply is impressed on diodeplates 25 and 26 exactly in synchronism with the A. C. supply impressedon plates H and I2. A resistance 29 is connected from the cathodeelement 30 to the center tap of resistance 28 and the grid element 3| isalso connected to the said center tap, so that the rectified supply isimpressed cn the resistance 29 to condition the grid element 3|periodically to render the imbe 24 conductive similarly as describedhereinabove.

It is evident that the grid bias of tube 24 varies similarly as the gridbias of tube I0 and in exactly the same time relationship; that is, whenthe grid bias of tube 24 is practically zero, this exact condition ispresent in tube ID. Thus, it is seen that the grids of tubes 10 and 24are conditioned in synchronism to render the respec tive tubesconductive (when the grid bias approaches zero value) and that the biason the said grids at all other times are of such value as to control theconductivity of the tubes so as to suppress the flow of current in theassociated output circuits. A condenser C and resistance R. are includedin the output circuit of the electric discharge device 24, and areconnected to the cathode element 30 of tube 24 and the anode element 32of the tube 33. The grid element 34 of the last mentioned tube isconnected to the secondary winding of transformer 35 and a source ofsupply to normally bias the tube 33 so that no current flows in itsoutput circuit.

Now, let it be assumed that the contacts 20 are maintained in anoperated position to initiate a series of short, equally spaced controlsignals which are received by any desired known type of receiving system36 associated with the secondary winding of transformer 35 or which maybe impressed directly on the said transformer in certain cases. Thereceived signals are effective to reduce the bias on the grid element 34of tube 33 and render this tube conductive at the particular intervalsthe signals are received. During the said intervals the control signalsare received, it is understood that the grid element 3| is soconditioned as to permit current to flow in the output circuit of tube24, for itwas described how the. tube 24 is rendered conductive at thesame intervals the tube ID is conditioned to initiate the control Acircuit is now established momentarily from the negative potentialsupply associated with the cathode element of tube 33, anode element 32thereof, condenser C I and resistance R to cathode and anode elements 30and 31, respectively, to a positive potential supply associated withsaid anode element. Energization of the described circuit chargescondenser C and the resulting voltage drop across the resistance R iseffective to reduce the bias on the associated grid element 38 of tube39 per mitting current to flow in its output circuit including thecontrol device 40 such as a relay or solenoid device or any otherdesired element, thereby controlling the operation of the device byvirtue of the currentfiow established in the said output circuit. Thevalues of C and R may be adjusted to control the operation of the tube39 in diflerent ways, namely, the said elements may be of such valuesthat the reception of the first signal of the series transmitted on asingle signal impulse is eflective to charge the condenser suflicientlyand effect a voltage drop across the resistance to render the tube 39conductive immediately to activate the associated control device and bemaintained charged sufficiently by the following impulses or signals tomaintain the bias on the grid element 38 reduced sufficiently to allow avirtually steady current to flow in the output circuit of tube 39; orthe values of the condenser and resistance may be so adjusted, forexample, that a predetermined number of signal impulses are necessary tobe received to charge sufliciently the condenser C to render the tube 39conductive. It is evident that such changes in values of the controlelements described to effect operation of the electric discharge devicesin a predetermined manner are encompassed in the scope of the presentinvention.

It has now been shown how the control or grid elements of two remotelysituated electric discharge devices are conditioned or controlled inexact time relationship by certain voltage conditions of a synchronousalternating voltage sup ply to control the conductivity of the saiddevices when the conditions of the said supply attain predeterminedvalues so as to initiate automatically control signals, either singly orin aseries which are equally spaced and timed with respect to eachother, to render the other said device efiective to control theoperation of ,an associated control element or device. It has been shownthat a. single signal impulse is eflective to render the controlledelement operative or that a series of predetermined timed signalimpulses is necessary to render operative the said control element tocontrol the element in a predetermined manner.

While there has been shown and described and pointed out the fundamentalnovel features of the invention as applied to a single modification, itwill be understood that various omissions and substitutions and changesin the form and details of the device illustrated and in its operationmay be made by those skilled in the art without departing from thespiritof the invention. It is the intention therefore to be limited onlyas indicated by the scope of the following claims.

What is claimed is: p

1. A system of the character described comprising a signal transmittingand receiving station, electric discharge means and a source ofsinusoidally varying voltage at each station, individual means forimpressing the voltage at each station upon the electric discharge meansthereat, means associated with each electric discharge means tocondition them in timed relationship when the voltages are impressedthereupon so that each discharge means can be rendered. conductive onlyat such timed intervals when the voltage attains a predeterminedpotential during each positive and negative period of each cycle, meansat the transmitting station to render the discharge means thereatconductive at the said timed intervals to initiate control sig nals,means for impressing the-signals upon the discharge means at thereceiving station to render it conductive, and control means at thereceiving station controlled by the last-mentioned discharge meanswhenever it is rendered conductive.

2. A system of the character described comprising a signal transmittingand receiving station, electric discharge means at each station,

sources of sinusoidally varying voltages and individual means at eachstation to connect a voltage source to each discharge means, individualmeans to render the said discharge means 0 at each station conductiveonly at such timed intervals when the voltage attains a predeterminedpotential during each positive and negative pe riod of each cycle, andmeans for transmitting and receiving signal impulses respectively atsaid transmitting and receiving stations whenever the said dischargemeans are rendered conductive.

3. A system of the character described in claim 2 wherein each of thesaid electric discharge means is provided with a control grid elementand means for varying the bias on said element in timed relationshipwith the said varying voltage whicliis impressed on the discharge meansfor controlling the conductivity thereof.

4. A system of the. character described having a signal transmitting andreceiving station,

individual means at the said stations for controlling the initiating andreceiving of signal impulses respectively comprising a source ofsinusoidally varying voltage, means for rectifying the voltage supply,an electric discharge device having a grid and anode circuit, means forvarying the bias impressed on the grid circuit in timed relationshipwith the said rectified voltage for rendering the device conductive eachtime the rectified voltage passes through zero, and con trol means,included in the anode circuit, energized each time the device isrendered conductive.

5. A system of the character described comprising a signal transmittingand receiving station, electric discharge means and a source ofsinusoidally varying voltage at each station, individual means forimpressing the voltage at each station upon the electric discharge meansthereat, means associated with each electric discharge means tocondition them in timed relationship when the voltages are impressedthereupon so that each discharge means can be rendered conductive onlyat such timed intervals when the voltage attains a predeterminedpotential each positive and negative period of each cycle, means uponthe discharge means at the receiving station for controlling theconductivity thereof in-' cluding additional means to render thelastmentioned discharge means conductive only upon receipt of apredetermined number of impulses of the said series, and control meansat the re ceiving station controlled by the said last-mentioneddischarge means whenever it is rendered conductive.

CLYDE J. FITCH.

